Networking with SIMH

The aim of this quick tutorial is to show how to setup SIMH's networking.

libpcap

By default SIMH supports networking via libpcap. The restrction of this method is that the host machine is unable to communicate with the emulator. Otherwise it's realitivly straight forward. First you need to make sure your binary has networking built in.

Showing host ethernet adapters

By issuing the command 'show xq eth' you will get either a list of adapters, or an error that this version does not support networking.

On the Windows platform it would look something like this:

With networking:

sim> show xq eth
ETH devices:
  0  \Device\NPF_GenericDialupAdapter                   (Adapter for generic dialup and VPN capture)
  1  \Device\NPF_{9E485825-641F-45C3-BC3B-E9DF4DDE520D} (Local Area Connection 4)
  2  \Device\NPF_{279EDB55-7802-44D3-8FA1-15B14452B309} (Local Area Connection)
sim>

Without networking:

sim> show xq eth
ETH devices:
  network support not available in simulator
sim>

Setting the MAC address

To set the MAC address to something other then the default (Which is important if you ever plan on having more then one SIMH device talking to another, say in HecNET) you need to change the MAC address. Remember this needs to be done before you attach the device. The command is simple as all you have to do is type in something to the effect of:

sim> set xq mac=00:00:01:00:00:01

Remember the first half is the vendor code, and the second half is the unique identifier. Do not use all 0's or all FF's it will create major issues on your network.

Attaching the device

Once the host ethernet adapter to bind to has been identified, the MAC address has been configured, you can now attach the emulator to the host network card. you can either specifiy the whole name as listed from the 'xq show dev' command, or use the corresponding number. Thusly:

att xq eth2

And

att xq \Device\NPF_{279EDB55-7802-44D3-8FA1-15B14452B309}

Are identical. You can now boot your emulator and it will have network accesss.

SLiRP

To be done later

Writing your own

To be done later